The importance of the interaction between solid internal surface and pore water for water transmission under hydraulic gradients and electrical and thermal potentials is pointed out. This interaction results in the establishment of a restrained water phase possessing characteristic mechanical, thermal, and electrical properties. If only a hydraulic gradient is established, the restraint can be expressed as a volume factor which, however, is also a function of the hydraulic gradient, especially at high values of the latter. The characteristic thermal and electrical properties of the interphase are the necessary conditions for thermo- and electro-osmotic flow. The basic theories of these phenomena are presented in a simple manner. The considerations presented and the equations derived hold only for such soils or similar systems that do not possess a significant gas phase.